桂林理工大学学报2017，Vol.37Issue(4)：580-586,7.DOI:10.3969/j.issn.1674-9057.2017.04.004
煤储层微裂缝对煤层气采收率影响的数值分析
Numerical analysis of microfractures effect on coal-bed methane reservoir ultimate recovery
摘要
Abstract
Microfractures are important space and seepage channel in coal reservoir,and important influence in its development on coal reservoir permeability,well production capacity and the change of recovery.In this paper,based on the scanning electron microscopy,mercury injection,adsorption test and production data,the effect of microfractures on coal reservoir productivity was comprehensively analyzed.The results show that the pore morphology of coal reservoir has the characteristics of homogenization because of the high coal rank,which is characterized by the pore size with different scales,but with a highly consistency (circular)shape.The two groups of diagenesis cleats in the coal rocks have obvious directivity,and their effectiveness is poor.The tectonic fractures in coal mainly contain the tensile and shear fractures,and their effectiveness is better.The gas saturation of coal samples was determined by the adsorption curve,formation pressure and the measured gas content data,they are mainly distributed in the range of 33.76％ and 73.52％.The effect of microfractures on coal bed methane reservoir ultimate recovery was discussed by the mercury injection experiment data and the improved material balance equation based on the production data.These two results are consistent with each other.Coalbed reservoir microfractures are developed with a higher capacity at the beginning of the production process,but declines fast later,and the ultimate recovery is lower.The production cycle of the coal reservoir where microfractures are relatively undeveloped is significantly longer than coal reservoir where microfractures are well developed.The recovery efficiency of coal-bed reservoir in this basin is about 50％,according to the calculation,the development cycle of the vertical CBM well is about 9-14 years.The ideal recovery efficiency of the coalbed reservoir obtained by the mercury injection experiment is about 70％,the needing time of this recovery is about 15-20 years.It takes a longer time for the coal-bed reservoir where microfractures are less developed to reach the ideal recovery than coal-bed reservoir where microfractures are well developed,and the cumulative gas production of the former is larger.关键词
微裂缝/煤层气/采收率/数值分析Key words
microfracture/coal-bed methane/ultimate recovery/numerical simulation分类
天文与地球科学引用本文复制引用
刘畅..煤储层微裂缝对煤层气采收率影响的数值分析[J].桂林理工大学学报,2017,37(4):580-586,7.基金项目
国家自然科学基金项目(41372139 （）
41072098) （）
国家科技重大专项课题(2016ZX05046-003-001) （2016ZX05046-003-001）
